This paper discusses the use of substance flow analysis （SFA） as a tool to support quantified research on urban drainage systems. Based on the principle of mass balance, a static substance flow model is established ...This paper discusses the use of substance flow analysis （SFA） as a tool to support quantified research on urban drainage systems. Based on the principle of mass balance, a static substance flow model is established to describe and examine the routes and intensities of water, chemical oxygen demand （COD）, total nitrogen （TN） and total phosphorus （TP） for a representative hypothetical city （RH city） in China, which is a devised and scaled city using statistical characteristics of urban circumstances at the national level. It is estimated that the annual flux of water, COD, TN and TP through the urban drainage system in 2010 was 55.1 million m3, 16037.3 t, 1649.5 t and 209.7 t, respectively. The effluent of wastewater treatment plant （WWTP） was identified as the most important pathway for pollutant emissions, which con- tributed approximately 60% of COD, 65% of TN and 50% of TP to receiving water. During the wastewater treatment process, 1.0 million m3, 7042.5 t, 584.2 t and 161.4 t of the four studied substances had been transmitted into sludge, meanwhile 3813.0 t of COD and 394.0 t of TN were converted and emitted to the atmosphere. Compared with the representative hypothetical city of 2000, urban population and the area of urban built districts had expanded by approximately 90% and 80% respectively during the decade, resulting in a more than threefold increase in the input of substances into the urban drainage system. Thanks to the development of urban drainage systems, the total loads of the city were maintained at a similar level.展开更多
China has become the largest producer of crude steel in the world since 1996, which places the country under huge pressure in terms of resources, energy, and the environment. Examining the driver of steel demand is of...China has become the largest producer of crude steel in the world since 1996, which places the country under huge pressure in terms of resources, energy, and the environment. Examining the driver of steel demand is of great significance to the structural adjustment and sustainable development of the steel industry. The researchers calculate the steel demand in China from 2000 to 2009 based on three sinks （steel stock, export, and loss） by taking the four stages of steel life cycle （production, fabrication and manufacturing, use, and waste manage- ment and recycling） as the study object. The researchers conclude that addition to in-use stock is the main driver of steel demand and that the 10-year average addition to in- use stock accounted for 77% of the steel sinks, in which 55% of the addition occurs in the building sector, and the steel for this segment is of low strength with large consumption. Based on the analysis of existing policies, the researchers propose that the steel demand structure will develop toward diversification and that the building sector will realize the upgrade of products as soon as possible to improve construction quality. Under the pressure of rising cost for imported resources, the export ratio of steel products should be controlled appropriately. Thus, recy- cling economy should be developed to reduce steel losses.展开更多
文摘This paper discusses the use of substance flow analysis （SFA） as a tool to support quantified research on urban drainage systems. Based on the principle of mass balance, a static substance flow model is established to describe and examine the routes and intensities of water, chemical oxygen demand （COD）, total nitrogen （TN） and total phosphorus （TP） for a representative hypothetical city （RH city） in China, which is a devised and scaled city using statistical characteristics of urban circumstances at the national level. It is estimated that the annual flux of water, COD, TN and TP through the urban drainage system in 2010 was 55.1 million m3, 16037.3 t, 1649.5 t and 209.7 t, respectively. The effluent of wastewater treatment plant （WWTP） was identified as the most important pathway for pollutant emissions, which con- tributed approximately 60% of COD, 65% of TN and 50% of TP to receiving water. During the wastewater treatment process, 1.0 million m3, 7042.5 t, 584.2 t and 161.4 t of the four studied substances had been transmitted into sludge, meanwhile 3813.0 t of COD and 394.0 t of TN were converted and emitted to the atmosphere. Compared with the representative hypothetical city of 2000, urban population and the area of urban built districts had expanded by approximately 90% and 80% respectively during the decade, resulting in a more than threefold increase in the input of substances into the urban drainage system. Thanks to the development of urban drainage systems, the total loads of the city were maintained at a similar level.
基金Project (2019YFC1907402) supported by the National Key R&D Program of ChinaProjects (51922108,52074363) supported by the National Natural Science Foundation of China+1 种基金Project (2019JJ20031) supported by the Hunan Natural Science Foundation,ChinaProject (2019SK2061) supported by the Hunan Key Research and Development Program,China。
基金We deeply appreciate the capital support given by the China Postdoctoral Science Foundation （20110490425）, the diligent work of data collectors, and the enlightenment provided by the SFA pioneers.
文摘China has become the largest producer of crude steel in the world since 1996, which places the country under huge pressure in terms of resources, energy, and the environment. Examining the driver of steel demand is of great significance to the structural adjustment and sustainable development of the steel industry. The researchers calculate the steel demand in China from 2000 to 2009 based on three sinks （steel stock, export, and loss） by taking the four stages of steel life cycle （production, fabrication and manufacturing, use, and waste manage- ment and recycling） as the study object. The researchers conclude that addition to in-use stock is the main driver of steel demand and that the 10-year average addition to in- use stock accounted for 77% of the steel sinks, in which 55% of the addition occurs in the building sector, and the steel for this segment is of low strength with large consumption. Based on the analysis of existing policies, the researchers propose that the steel demand structure will develop toward diversification and that the building sector will realize the upgrade of products as soon as possible to improve construction quality. Under the pressure of rising cost for imported resources, the export ratio of steel products should be controlled appropriately. Thus, recy- cling economy should be developed to reduce steel losses.
